12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaSEA WATER DISTRTICT COOLING FEASIBILITY ANALYSIS FOR TALLINNA. Hani 1 , I. Britikovski 1 , H. Voll 1 and T.-A. Kõiv 11Tallinn University of Technology, Department of Environmental Engineering, EstoniaABSTRACTIn this paper sea water district cooling feasibilityanalysis for Tallinn is presented. It has become moreand more interesting to study alternative solutions forpublic buildings A/C cooling due to relatively highelectrical energy prices. Besides economical aspectstechnical and environmental sides must be considered.INTRODUCTIONalso important to locate the district cooling station nearto energy source.Typical SW district cooling system principle is indicatedin Figure 1. The system consists of three mainsections:Cold sea water pumping;Cooling plant with heat exchangers;Standard cooling distribution network.The first large district cooling systems were developedduring the 1960‘s in Hartford (1962) and California(1965) in United States [10]. The first systems inEurope were La Defense (1967) in France and inHamburg (1968) Germany [1]. In the beginning of the70`s the first system in Japan (Shinjuku) was built [3].However, because of the energy crises in the end of70`s, the District Cooling development was slow and nonew large systems were built. Until the end of 80`swhen many new large systems were opened forexample Kioi-cho, Nishi-Shinjuku in Japan and TrigenTrenton in United States. Also the first district coolingsystem of the Nordic countries was installed in Norway.Operation started in 1989 in Baerum, near Oslo. Thefirst system in Sweden was built in 1992 in Västerås [2]and since then the district cooling in Sweden hasdeveloped rapidly. Since the 1990‘s the establishmentof commercial district cooling systems has increasedrapidly worldwide. Nowadays, more than 20 countrieshave a commercial district cooling system and this isexpected to increase rapidly [4].The sea water (SW) district cooling is based on largenatural cold water source. Enough cold water isaccumulated in lakes, seas, oceans, rivers, etc [8].Lowering the coolant temperature with sea water is analternative to conventional electrical energy consumingchillers [5]. The system working principle is quite similarto geothermal energy production which is used inheating systems [6]. Until now the sea water districtcooling is quite conservatively expanded around theWorld.SW DISTRICT COOLING PRINCIPLEThe temperature in conventional cooling water networkis between +4…+7 o C so applicable the sea watertemperature should be below +5 oC . Despite thatcompressor based cooling can be used in case coolingwater temperature is higher than mentioned [9]. It is153Fig. 1 SW district cooling principle schematicHeat exchangers allow usage of the soft water indistribution network while problematic salty sea waterhandling will be done in open central circuit.Environmental impact study is required before any ofthe projects will be executed. Large sea waterquantities have to be available to minimize pumpingimpacts. In addition to evaluation of the deep zone coldwater pumping, the analysis of recycling the sea waterback to lower sea water zone with higher temperaturesshould be made.Following factors shall be considered before systemdesign [7]: Minimum altitudes between heat exchangers andwater resource level should be designed; Centralized district cooling plant (heat exchangers,pumping station and chillers) is less expensivethan decentralised system; Centralized system has less maintenanceproblems.DESIGN PARAMETERSTemperature of the sea water varies during differentseasons and distance from the coast.